Field of the Invention
The invention lies in the field of internal combustion engines. The invention relates to a method for controlling an internal combustion engine. In a method according to German Published, Non-Prosecuted Patent Application 42 32 974 A1, an estimated value of an ignition-angle-standardized actual torque is determined. A setpoint value of a torque that is to be set by the air mass flow rate is determined in a device for specifying torque values. The setpoint value of the torque is corrected as a function of a deviation of the setpoint value from the standardized estimated value of the torque. The corrected setpoint value of the torque is assigned to a setpoint value of the air mass flow rate as a function of the rotational speed, the value then being set by a corresponding degree of opening of a throttle valve. An ignition angle is adjusted as a function of the deviation of the setpoint value from the standardized estimated value of the torque.
If the determination of the torque setpoint value is additionally performed taking into account various torque requests, for example (1) of a traction controller, (2) of a torque derivative action for heating a catalytic converter, or (3) a torque request of an engine drag torque controller, deviations between the standardized estimated value of the torque and the setpoint value of the torque occur even during steady-state operation of the internal combustion engine. The air mass flow rate, assigned to the corrected setpoint value of the torque, in a cylinder of the internal combustion engine cannot be set until after a long delay time. Accordingly, the correction of the torque as a function of the setpoint value and of the estimated value of the torque gives rise to severe oscillations in the air mass flow rate, thus giving rise to a need for adjusting the ignition angle. Such adjustment results in a reduction of driving comfort and an increase in emissions.
A method for setting the torque on an internal combustion engine is disclosed in German Patent No. 43 15 885 C1. A regulator having the air mass flow rate as the controlled variable is provided and generates an actuation signal for a throttle valve. The system deviation of the regulator is formed from an average air mass flow rate, which is calculated using an inversely clocked load filter as a function of a predefined load setpoint value, and a measured air mass flow rate.